widgets: Add text widget

Automatic text scaling to fill an area

widgets/constrainedtext.lua

@@ -0,0 +1,126 @@
+local color      = require( "gears.color" )
+local pango      = require( "lgi"         ).Pango
+local pangocairo = require( "lgi"         ).PangoCairo
+local wibox      = require( "wibox"       )
+local beautiful  = require( "beautiful"   )
+local scale        = pango.SCALE
+
+local function setup_dpi(box, dpi)
+    if box._private.dpi ~= dpi then
+        box._private.dpi = dpi
+        box._private.ctx:set_resolution(dpi)
+        box._private.layout:context_changed()
+    end
+end
+
+--- Setup a pango layout for the given textbox and dpi
+local function setup_layout(box, width, height, dpi)
+--     box._private.layout.width  = pango.units_from_double(width) --FIXME...
+    box._private.layout.height = pango.units_from_double(height)
+    setup_dpi(box, dpi)
+end
+
+local function fit(self, context,width,height)
+
+    setup_layout(self, width, height, context.dpi)
+
+    -- Compute the optimal font size
+    local padding   = self._private.padding or 0
+    local tm        = self._private.top_margin or 0
+    height          = math.max(0, height - tm)
+    local min       = math.min(width, height)
+    local font_size = math.max(0, min - 2*padding)
+
+    if self._private.force_text then
+        self._private.layout.text = self._private.force_text
+    end
+
+    self._private.desc:set_size( font_size * scale )
+    self._private.layout:set_font_description(self._private.desc)
+
+    local _, geo = self._private.layout:get_pixel_extents()
+
+    if self._private.force_text then
+        self._private.layout.text = self._private.text
+    end
+
+    return math.min(geo.width, width), math.min(geo.height + tm, height)
+end
+
+local function draw(self, context, cr, width, height)
+    -- Some layouts never call fit()...
+    fit(self, context, width, height)
+    cr:update_layout(self._private.layout)
+
+    local _, geo = self._private.layout:get_pixel_extents()
+    local tm     = self._private.top_margin or 0
+    local size   = math.min(width, height - tm)
+
+    -- Translate the canvas to center the text
+    local dy = ( size - geo.height  )/2 - geo.y + tm
+    local dx = ( size - geo.width   )/2 - geo.x
+
+    cr:move_to(0, dy)
+
+    -- Show the text
+    cr:show_layout(self._private.layout)
+end
+
+local function set_text(self, text)
+    if tostring(text):len() == 1 then text = text.."_" end--FIXME...
+    self._private.layout.text = text
+    self._private.text = text
+    self:emit_signal("widget::redraw_needed")
+    self:emit_signal("widget::layout_changed")
+end
+
+local function set_padding(self, padding)
+    self._private.padding = padding
+    self:emit_signal("widget::redraw_needed")
+    self:emit_signal("widget::layout_changed")
+end
+
+local function set_top_margin(self, margin)
+    self._private.top_margin = margin or 0
+    self:emit_signal("widget::redraw_needed")
+    self:emit_signal("widget::layout_changed")
+end
+
+local function set_width_for_text(self, text)
+    self._private.force_text = text
+    self:emit_signal("widget::redraw_needed")
+    self:emit_signal("widget::layout_changed")
+end
+
+local function new(text, padding, top_margin)
+    local wdg = wibox.widget.base.empty_widget()
+
+    -- Add the basic functions
+    rawset(wdg, "draw"              , draw               )
+    rawset(wdg, "fit"               , fit                )
+    rawset(wdg, "set_padding"       , set_padding        )
+    rawset(wdg, "set_top_margin"    , set_top_margin     )
+    rawset(wdg, "set_text"          , set_text           )
+    rawset(wdg, "set_width_for_text", set_width_for_text )
+
+    -- Create the pango objects
+    local pango_crx = pangocairo.font_map_get_default():create_context()
+    local pango_l   = pango.Layout.new(pango_crx)
+    local desc      = pango.FontDescription()
+    pango_l:set_alignment("CENTER")
+    desc:set_family( "Verdana"         )
+    desc:set_weight( pango.Weight.BOLD )
+
+    wdg._private.layout = pango_l
+    wdg._private.desc   = desc
+    wdg._private.ctx   = pango_crx
+    wdg:emit_signal("widget::layout_changed")
+
+    if text       then set_text      (wdg, text      ) end
+    if padding    then set_padding   (wdg, padding   ) end
+    if top_margin then set_top_margin(wdg, top_margin) end
+
+    return wdg
+end
+
+return setmetatable({}, { __call = function(_, ...) return new(...) end })

widgets/init.lua

@@ -8,4 +8,5 @@ return {
     piechart        = require( "radical.widgets.piechart"        ),
     separator       = require( "radical.widgets.separator"       ),
     infoshapes      = require( "radical.widgets.infoshapes"      ),
+    constrainedtext = require( "radical.widgets.constrainedtext" ),
 }